feat(photon): auto-configure allowlist and cron channel on setup

During `hermes photon setup`, allowlist the operator's number and set
their DM as the cron home channel when those env vars are unset. Without
this, the gateway denies the operator's own messages and cron has no
default delivery target. Re-runs never overwrite hand-tuned values.

Also teaches the sidecar's `resolveSpace` to accept a bare E.164 number
as a space identifier, resolving it to the user's DM space so
`PHOTON_HOME_CHANNEL` can be set to a phone number instead of an opaque
space id.

tests/plugins/platforms/photon/test_setup_access.py

@@ -0,0 +1,38 @@
+"""Tests for `hermes photon setup`'s access auto-configuration.
+
+`_autoconfigure_access` allowlists the operator and points the cron home
+channel at their DM, writing to the per-test ~/.hermes/.env (the hermetic
+HERMES_HOME fixture isolates this). It must fill only unset keys so a re-run
+never clobbers a hand-tuned allowlist.
+"""
+from __future__ import annotations
+
+import pytest
+
+from hermes_cli.config import get_env_value, save_env_value
+from plugins.platforms.photon import cli
+
+
+def test_autoconfigure_access_fills_unset(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.delenv("PHOTON_ALLOWED_USERS", raising=False)
+    monkeypatch.delenv("PHOTON_HOME_CHANNEL", raising=False)
+
+    cli._autoconfigure_access("+15551234567")
+
+    assert get_env_value("PHOTON_ALLOWED_USERS") == "+15551234567"
+    assert get_env_value("PHOTON_HOME_CHANNEL") == "+15551234567"
+
+
+def test_autoconfigure_access_preserves_existing_allowlist(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.delenv("PHOTON_ALLOWED_USERS", raising=False)
+    monkeypatch.delenv("PHOTON_HOME_CHANNEL", raising=False)
+    # A hand-tuned allowlist already in place must survive a setup re-run.
+    save_env_value("PHOTON_ALLOWED_USERS", "+19998887777,+15551112222")
+
+    cli._autoconfigure_access("+15551234567")
+
+    assert get_env_value("PHOTON_ALLOWED_USERS") == "+19998887777,+15551112222"
+    # The still-unset home channel is filled.
+    assert get_env_value("PHOTON_HOME_CHANNEL") == "+15551234567"